Field of the Invention
The present invention relates to an apparatus for measuring levels of materials, especially of fluids, and optionally for calculating a density profile of a mixed fluid system.
Description of the Related Art
A density profiler has been described in WO2000/022387. The device comprises a linear array of sources of ionising radiation which emit radiation towards detectors disposed in one or more linear arrays. When the source array and detector array(s) are positioned so that they traverse the interfaces between two or more fluids in a container, the interfaces of the fluids may be identified from the differences in radiation received by each detector in the array. The device has been successfully deployed for use in storage tanks and oil separators. In some circumstances it is required to operate density profilers in cold environments or where there is a risk that the instrument will be subjected to very low temperatures at certain times. Many electronic instruments are sensitive to operation in extreme temperatures and electrical components may be prone to failure or may not be certified for operation at extremely low temperatures. It is therefore an object of the invention to provide a detector probe suitable for use in a density profiler or other nucleonic level measurement system which may be operated at low environmental temperatures.